package com.ng.config;

import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;
import org.springframework.http.converter.json.Jackson2ObjectMapperBuilder;

import com.fasterxml.jackson.annotation.JsonInclude.Include;
import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.ObjectMapper;

/**
 * 〈返回json空值去掉null和""〉 〈功能详细描述〉
 * 
 * @author lyf
 * @see JacksonConfig
 * @since
 */
@Configuration
public class JacksonConfig {
	@Bean
	@Primary
	@ConditionalOnMissingBean(ObjectMapper.class)
	public ObjectMapper jacksonObjectMapper(Jackson2ObjectMapperBuilder builder) {
		ObjectMapper objectMapper = builder.createXmlMapper(false).build();
		objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
		// 通过该方法对mapper对象进行设置，所有序列化的对象都将按改规则进行系列化
		// Include.Include.ALWAYS 默认
		// Include.NON_DEFAULT 属性为默认值不序列化
		// Include.NON_EMPTY 属性为 空（""） 或者为 NULL 都不序列化，则返回的json是没有这个字段的。这样对移动端会更省流量
		// Include.NON_NULL 属性为NULL 不序列化,就是为null的字段不参加序列化
  		 objectMapper.setSerializationInclusion(Include.NON_NULL);

		// 字段保留，将null值转为"" -- 将为null的全部去掉
//		objectMapper.getSerializerProvider().setNullValueSerializer(new JsonSerializer<Object>() {
//			@Override
//			public void serialize(Object o, JsonGenerator jsonGenerator, SerializerProvider serializerProvider)
//					throws IOException, JsonProcessingException {
//				jsonGenerator.writeString("");
//
//			}
//		});
		return objectMapper;
	}
	
	
}
